Research on optimization design of PWR flow distribution device based on numerical simulation

ABSTRACT

In the lower chamber of pressurized water reactor (PWR), the flow distribution device is the core module to distribute coolant into the core. It has complex structure and numerous design parameters. Therefore, it has important theoretical and practical significance to optimize the device. The mesh independence verification, turbulence model selection, and data processing all can influence the numerical simulation results of the lower chamber, in order to research the influence, a numerical simulation method based on the original model of CNP1000 reactor lower chamber is proposed in this paper. In the method, an optimization design method of flow distribution device is established based on surrogate model. The main design variables and optimization objectives are determined based on the device’s structure and function characteristics. And then it respectively adopts Kriging algorithm and multi-objective genetic algorithm to establish a surrogate model of flow distribution device and optimize it globally. Finally, the optimal design variables are obtained. Compared with the device’s performance before optimization, the after optimization has smaller total pressure loss and more uniform flow. The effectiveness and practicability of proposed optimization design method can be verified.     

Bioelectronic protein nanowire sensors for ammonia detection

Electronic sensors based on biomaterials can lead to novel green technologies that are low cost, renewable, and eco-friendly. Here we demonstrate bioelectronic ammonia sensors made from protein nanowires harvested from the microorganism Geobacter sulfurreducens. The nanowire sensor responds to a broad range of ammonia concentrations (10 to 10⁶ ppb), which covers the range relevant for industrial, environmental, and biomedical applications. The sensor also demonstrates high selectivity to ammonia compared to moisture and other common gases found in human breath. These results provide a proof-of-concept demonstration for developing protein nanowire based gas sensors for applications in industry, agriculture, environmental monitoring, and healthcare.

     

煤炭企业应收货款风险控制

通过对影响货款回收及货款安全主要因素的分析,提出了确保煤炭货款及时回收、有效控制货款风险的途径和措施.     

潲水油脱色工艺研究

研究了双氧水和活性白土联合使用对潲水油脱色效果的影响,分析了吸附和氧化两种方法各自的影响因素.确定了潲水油的最佳脱色条件为:潲水油中加入3.5%(占油质量)的双氧水,60℃下搅拌反应20 min;再加入5%的活性白土,维持温度60℃不变,搅拌25 min可以达到理想的脱色效果.     

基于自然对流的控制棒驱动机构温场研究

在新一代反应堆控制棒驱动机构耐温等级提升后,为分析取消控制棒驱动机构强制通风系统是否可行,建立了基于单台控制棒驱动机构流场的计算模型,合理确定了求解方法和边界条件,并通过与试验结果进行拟合,进行了控制棒驱动机构群全尺寸模型的温场和速度场计算,得到基于自然对流的控制棒驱动机构温场效应。研究结果表明,通过自然对流可以将控制棒驱动机构运行产生的热量完全带出堆坑,不存在堆坑窝热情况,并且随着控制棒驱动机构群总输出功率的增加,堆顶区域的自然循环强度也增加,可以达到冷却控制棒驱动机构的效果。因此,耐温等级提升后的控制棒驱动机构可以取消强制通风。      

An Effective Sneak-Path Solution Based on a Transient-Relaxation Device

An efficient strategy for addressing individual devices is required to unveil the full potential of memristors for high-density memory and computing applications. Existing strategies using two-terminal selectors that are preferable for compact integration have trade-offs in reduced generality or functional window. A strategy that applies to broad memristors and maintains their full-range functional window is proposed. This strategy uses a type of unipolar switch featuring a transient relaxation or retention as the selector. The unidirectional current flow in the switch suppresses the sneak-path current, whereas the transient-relaxation window is exploited for bidirectional programming. A unipolar volatile memristor with ultralow switching voltage (e.g., <100 mV), constructed from a protein nanowire dielectric harvested from Geobacter sulfurreducens, is specifically employed as the example switch to highlight the advantages and scalability in the strategy for array integration.     

计算机辅助决策系统在电网规划中的应用

针对镇江地区的发展特点 ,应用先进的《城市电网规划计算机辅助决策系统》软件 ,采用规划策略和优化模型 ,在科学合理的负荷及负荷分布预测基础上 ,对城市高压网架结构、中压配电网网架结构、变电站布点及供电范围进行全面优化 ,并完成可靠性定量分析和经济性分析 ,给出高水平的规划成果。通过电网优化规划 ,可极大提高电力企业投资效益 ,降低电网的网络损耗 ,提高供电可靠性 ,全面提高电网的运行管理水平。     

低温工况下结霜对翅片管蒸发器性能影响研究

翅片管蒸发器的结霜将增加空气压降，增大传热热阻，从而直接影响到蒸发器的效率及空气侧平均换热系数，本文就低温工况下，结霜对蒸发器性能的影响进行了测试研究，为翅片管蒸发器的设计应用提供了重要依据。     

Membrane combination technic on treatment and reuse of high ammonia and salts wastewater in rare earth manufacture process

With the rapid development of rare earth industry in China,high NH3-N and high salts wastewater generated in rare earth manufacture process had caused serious environment pollution especially for surrounding water body.Traditional treatment processes were either incapable of reducing pollutants concentration to the levels regulated by law or prohibitively expensive and difficult to operate.In this paper,a hybrid process which integrated air stripping pretreatment and low pressure reverse osmosis(LPRO) was proposed to treat this wastewater containing high ammonia and salt.Mechanism of treatment and remediation of ammonia and salt polluted water body was investigated.Influences of temperature,pH,and air stripping time on removal ratio of ammonia efficiencies were also discussed.Relationship among trans-membrane pressure drop(ΔP),additions ratio,stability of membrane and the possibility of water reuse were studied.The results showed that removal ratio of ammonia after LPRO desalination process could reach up to 98%,fluoride amounted to more than 99% and desalt efficiencies reached up to 95%,and stripped gas ammonia could be effectively recovered.Water quality had been improved significantly to meet reuse or discharge standards.     

Combined time- and wavelength-division-multiplexing demodulation technique of fiber grating sensor arrays using a tunable pulsed laser

Combined time- and wavelength-division-multiplexing demodulation technique of fiber Bragg grating (FBG) sensor arrays using a tunable pulsed laser is proposed and demonstrated. A tunable fiber laser based on a matched FBG is applied. The wavelengths of the sensing FBGs are obtained by detecting the maximum voltages with a photodiode that avoids the complex demodulation process. The advantages of this scheme are simple structure, high signal-to-noise ratio, and the sensing signals obtained by detecting the maximum voltages.